The Mapster WP Maps plugin for WordPress is vulnerable to Arbitrary User Meta Write in all versions up to, and including, 1.23.0 via the `my_profile_update()` function. This is due to the function performing no nonce verification, no capability check, and no allowlist validation on the meta key supplied via the `acf-photo-gallery-groups` POST parameter before passing both the meta key and its corresponding value directly to `update_user_meta()`. This makes it possible for authenticated attackers, with Subscriber-level access and above, to update arbitrary user meta values, though privilege escalation is not possible.